Delayed hypersensitivity in ampicillin-induced toxic epidermal necrolysis.

A patient with ampicillin-induced toxic epidermal necrolysis (TEN) showed pronounced delayed hypersensitivity to ampicillin sodium by both intradermal and patch tests. In addition, a positive lymphocyte transformation test to ampicillin was demonstrated by an in vitro study. On the basis of these findings and the data found in the literature, we believe that delayed hypersensitivity plays a crucial role in the development of drug-induced TEN. We recommend patch testing with suspected medication in such cases.